This invention relates generally to truss fabrication systems, and in particular to an obstruction detection device for a truss fabrication system.
Pre-manufactured structural frameworks, such as trusses, are widely used in the construction industry for forming a roof, wall panel, floor, or other building component. Each truss includes a collection of wooden, plastic, or metallic truss members held together by connectors, such as nailing plates. The trusses are assembled to the correct specifications at a factory and then shipped to a construction site. A truss fabrication system is frequently used to facilitate efficient assembly of the truss. It features a table on which the truss members and connectors are placed at desired relative positions to form the particular truss configuration. A gantry press then travels along the table to press the connectors into the truss members thereby joining them together. Typically, the gantry press includes a cylindric roller mounted on a gantry. The gantry has wheels which run on tracks or guides located on the sides of the table or on the floor next to the sides of the table. After traversing the length of the table, the roller apparatus continues moving along the guides and is stopped in a parking area at an end of the table such that the assembled truss can be freely removed from the table without obstruction by the roller apparatus.
Gantry presses are equipped with devices to detect obstructions in the path of the gantry press and to stop the press. For example, many gantry press devices have a single, horizontal rod supported outwardly from the press for detecting obstructions along the path of travel. The horizontal rod is typically supported at its ends by two inclined arms pivotally mounted near the base of each of the opposite sides of the gantry. The horizontal rod extends the approximate length of the gantry press and is positioned such that the truss table and any truss components thereon may pass under the rod without being contacted. The rod is coupled with a motor shut-off switch to stop the gantry press from traveling along the pathway when the rod is pivoted upward as a result of either the rod or the arms encountering an obstruction.